Cryptic extinction of a common Pacific lizard Emoia impar (Squamata, Scincidae) from the Hawaiian Islands R OBERT F ISHER and I VAN I NEICH Abstract Most documented declines of tropical reptiles are Introduction of dramatic or enigmatic species. Declines of widespread species tend to be cryptic. The early (1900s) decline and xtinctions on islands are rampant and have many extinction of the common Pacific skink Emoia impar from Ecauses. For reptiles, particularly lizards, insular extinc- the Hawaiian Islands is documented here through an tions greatly exceed those of mainland species and the assessment of literature, museum vouchers and recent extinction of smaller lizard species is rarely documented 1991 fieldwork. This decline appears contemporaneous with the (Case et al., ). Incomplete knowledge of island fauna documented declines of invertebrates and birds across the hinders an understanding of the true loss of diversity from Hawaiian Islands. A review of the plausible causal factors these ecosystems, and the issue of morphologically cryptic fi indicates that the spread of the introduced big-headed ant species also masks quanti cation of these extirpations or 2007 fi Pheidole megacephala is the most likely factor in this lizard extinctions (Bickford et al., ). The Paci c Basin ’ decline. The introduction and spread of a similar skink contains the majority of the world s tropical islands. These Lampropholis delicata across the islands appears to are most often inhabited by lizards of the families Scincidae 1995 1996 temporally follow the decline of E. impar, although there and Gekkonidae (Adler et al., ; Allison, ; Fisher, 1997 is no evidence of competition between these species. It ). Various hypotheses exist for the dispersal of lizards appears that L. delicata is spreading to occupy the niche across vast oceanic barriers and these include both natural 1985 1997 vacated by the extirpated E. impar. Further confusion exists and anthropogenic processes (Gibbons, ; Fisher, ; 2008 because the skink E. cyanura, which is very similar in Keogh et al., ). We have much less evidence for the appearance to E. impar, appears to have been introduced to extinction of insular lizard populations. 1 one site within a hotel on Kaua’i and persisted as a The Hawaiian Islands (Fig. ) are one of the most isolated population at that site for approximately 2 decades (1970s– archipelagos and have experienced spectacular radiations of 1990s) but is now also extirpated. This study highlights the theirbiota,particularlyinvertebratesandbirds(Zimmerman, 1970 2008 cryptic nature of this early species extinction as evidence ; Cowie & Holland, ). They contain a small lizard 1996 that current biogeographical patterns of non-charismatic or fauna that is thought to be of recent origin (McKeown, ; 1997 1999 enigmatic reptiles across the Pacific may be the historical Fisher, ; Austin, ), although this assumption is result of early widespread invasion by ants. Conservation untested for some skinks (Cryptoblepharus and Emoia). 1987 1 and restoration activities for reptiles in the tropical Pacific James et al. ( ; see their Table ) provided evidence of an should consider this possibility and evaluate all evidence early fossil lizard bone that predates humans on the islands, prior to any implementation. leaving open the question of natural dispersal to the islands. Most of the documented extinctions from the Hawaiian Keywords Emoia impar, Hawaiian Islands, invasive ants, Islandshavebeenfromitsbird,insectandsnailradiationsand Lampropholis delicata, lizard extinction, Pheidole mega- many hundreds of species are now threatened (Cowie & cephala, Scincidae Holland, 2008). Because of their role in international com- mercial routes the Hawaiian Islands have experienced major This paper contains supplementary material that can be invasions of exotic species; for example, . 2,000 invertebrate found online at http://journals.cambridge.org species (Howarth, 1985) and many reptiles and amphibians (McKeown, 1996; Kraus, 2002, 2009; Kraus & Duvall, 2004). Girard (1858) provided the first species list of Hawaiian reptiles but the first detailed study of reptiles was made by Stejneger (1899). Subsequent studies (McGregor, 1904; 1917 1941 1953 ROBERT FISHER (Corresponding author) U.S. Geological Survey, Western Snyder, ; Tinker, ; Oliver & Shaw, ; Hunsaker Ecological Research Center, San Diego Field Station, 4165 Spruance Road, & Breese, 1967; McKeown, 1996) followed and offer a fi Suite 200, San Diego, California 92101-0812, USA. E-mail r [email protected] potential history of the appearance and disappearance of IVAN INEICH Muséum national d’Histoire naturelle, Département de species. These data indicate that when Europeans arrived Systématique et Evolution, UMR 7205 (Origine, Structure et Evolution de la Biodiversité), CP 30 (Reptiles), Paris, France three species of skinks (Cryptoblepharus poecilopleurus, Received 17 September 2010. Revision requested 4 November 2010. Emoia impar [as cyanura and schauinslandi], and Lipinia Accepted 9 December 2010. First published online 12 March 2012. noctua) were present on the Hawaiian Islands. © 2012 Fauna & Flora International, Oryx, 46(2), 187–195 doi:10.1017/S0030605310001778 Downloaded from https://www.cambridge.org/core. IP address: 170.106.40.40, on 25 Sep 2021 at 09:36:44, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605310001778 188 R. Fisher and I. Ineich FIG. 1 The large southern islands of the Hawaiian Archipelago. Historical records for Emoia impar were documented from all of these islands except Lanai. The invasive species Lampropholis delicata has now been recorded from all these islands. The exotic Emoia cyanura was only recorded for a limited period of time, from Kauai. Until recently Emoia cyanura was considered a single delicata (originating from Australia) as part of our species across the Pacific Basin but morphological and assessment of extinction of Hawaiian Emoia. The three ecological analysis by Ineich (Ineich, 1987a,b; Ineich & Zug, taxa are ecologically similar as generalist diurnal ground 1991) indicated that there were two species (E. cyanura and skinks. Of the other skinks, the snake-eyed skink E.impar)sympatricacrossthislargeregion.Earlyrecognition Cryptoblepharus poecilopleurus is restricted to rocky or that Hawaiian Emoia had two distinct forms led Werner corallian shorelines of the Hawaiian Islands, and the moth (1901) to the recognition of a blue striped one and a melanistic skink L. noctua is semi-burrowing and semi-arboreal in the one, although these are colour morphs of the same species. Islands. They are members of E. impar, and this species is the only Emoia species that occurred historically on the Hawaiian Literature review Islands. This confusion, and the recent introduction of E. cyanura, confounded a full understanding of the history of We reviewed all available literature on Hawaiian reptiles, Emoia in the islands. Here we examine literature reports and including the main islands and the north-western islands, museum specimens and report field surveys to assess the focusing on E. cyanura, E. impar and L. delicata. We tried to current status of this genus on the Hawaiian Islands. determine the validity of each report of these species and to locate museum specimens vouchering the reports. Data Methods come from both the primary and grey literature. Combining literature and museum data with recent field- Museum surveys work we trace the historical and recent occurrence of E. cyanura and E. impar across the Hawaiian Islands. We We examined E. impar and E. cyanura specimens in the also collected data on the recently introduced Lampropholis major museums and confirmed the specific identity of © 2012 Fauna & Flora International, Oryx, 46(2), 187–195 Downloaded from https://www.cambridge.org/core. IP address: 170.106.40.40, on 25 Sep 2021 at 09:36:44, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605310001778 Cryptic extinction 189 TABLE 1 Distribution and collecting periods for Emoia cyanura, Emoia impar and Lampropholis delicata on the Hawaiian Islands (Fig. 1). The numbers in the cells represent the number of museum vouchers recorded from that decade. Species Decade of record (by island) 1800–1899 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Total Hawaii L. delicata 12218152682 E. impar 8 8 Kauai E. cyanura 13 1 14 L. delicata 1 1 31 18 6 74 22 153 E. impar 17 1 1 1 20 Lanai L. delicata 50 9 59 Maui L. delicata 2171635 E. impar 21 5 26 Molokai L. delicata 55 1 18 74 E. impar 14 14 Oahu L. delicata 15 7 5 10782829312549295 E. impar 11 2 13 No island listed E. impar 1 1 Hawaiian specimens. Additionally, we used online collec- could not confirm the presence of E. impar after 1902 in any tion query tools (Herpnet, Global Biodiversity Information publication. We also found no records for any Emoia on the Facility) to determine the presence of additional specimens north-western islands and could confirm the occurrence of and, where possible, examined the specimens to confirm Emoia only from Kaua’i, Oahu, Molokai, Maui and Hawai’i identification. Only specimens with detailed island locations Island (Appendix). Emoia have never been reported from are considered. When known, the date of collection is any smaller offshore islets. reported in parentheses. See footnote to Appendix for La Rivers’ (1948) general ecological study near the Pearl museum acronyms. Harbor area of Oahu in 1944/1945 reported a skink as E. cyanura. He encountered only one species of skink. All Field surveys 1940s Oahu skink voucher specimens (. 100)are Lampropholis, most from Honolulu and a couple from We surveyed the historical localities for all reported Pearl Harbor. Thus L. delicata was the dominant ground Hawaiian Emoia to determine the current presence of dwelling skink, and he mistakenly identified his specimens skinks. We used visual encounter transects and random as E. cyanura. We searched for voucher specimens from La searches. All surveys were during daytime under appro- Rivers’ study and found none. Oliver & Shaw (1953) priate weather conditions (sunny or partial clouds).